This invention relates to a seal assembly for providing an articulated connection between pipes, particularly hot exhaust gas pipes. The seal assembly is of the type which has a first flange affixed to the end of one pipe and provided with a first metallic slide face coaxial with the pipe axis. The seal assembly further has a second flange affixed to the end of the other pipe, a second metallic slide face which is held operationally stationarily on the second flange and is coaxial with the pipe axis. The second metallic slide face is surrounded by the first slide face and is in sliding engagement therewith. At least one of the two slide faces has a spherical annular surface. The seal assembly also includes a device which maintains the two slide faces in contact with one another with an axial bias.
In known seal assemblies of the above-outlined type the second metallic slide face is formed immediately at the second flange as a complemental convex spherical annular surface. The second flange is in contact with the first slide face directly or with the interposition of an elastic sealing member. Such seal assemblies are used in particular in conduits for pressurized fluid.
In case of hot exhaust gas pipes, in particular, exhaust pipes of internal combustion engines, it is known to form the second slide face on sealing rings supported on the second sealing flange. The sealing rings have metal fabric inserts which project from the surface.
In known seal assemblies problems have been encountered as concerns the durability and noise generation during relative pivotal motions of the two pipes. It has been found that these problems are rooted, particularly in hot pipes, in the so-called "slip-stick" effect on the relatively moving slide faces. The known measures for eliminating these difficulties, such as the use of graphite with or without an additional lubricant as the filler between the woven metal insert and further, the use of sacrificial (self exhausting) wires having superior sliding properties were not found to be satisfactory because of poor durability and/or high costs.